Barometric draft control



Jan. 30, 1951 A. o. DADY BAROMETRIC DRAFT CONTROL 5 Sheets-Sheet l Filed April 19, 1947 :ide-@H41 `Lan. 30, 1951 Filed April 19, 1947 A. o. DADY 2,539,815

BAROMETRIC DRAFT CONTROL 3 Sheets-Sheet 2 Jan. 30, 1951 A. o. DADY 2,539,815

BAROMETRIC DRAFT CONTROL.

5 Sheets-Sheet 3 Filed April 19, 1947 )24a @X 23a' Patented Jan. 30, 1951 BAROMETRIC DRAFT CONTROL Arthur 0. Dady, Flossmoox', ll., assigner to Sears, Roebuck and Co., Chicago, Ill., a corporation of New York Application April 19, 1947, Serial No. 742,533

12 Claims.

My invention relates to barometrio draft controls for furnaces, and has to do more particularly with a control of this type which will be simple and inexpensive in construction and smooth in operation, so as to provide more delicate and certain control of the fire than devices of this type which have previously been known.

Barometric draft controls have been known for a long time, and serve to stabilize the available furnace draft so as to maintain the most eli-lcient operating conditions of the re bed regardless of external factors, such as wind.

A particular object of the present invention is to provide a barometric control in which the valve blade is hingedly supported by means of improved knife-edge bearings so that it is extremely sensitive to slight variations in pressure within the stack. l

Still another object is to provide a device of the type referred to which will give a constant or nearly constant draft intensity within a combustion chamber regardless of such external effects as wind velocity, outside temperature, stack temperature, etc. Obviously, by providing a constant draft, a correspondingly constant amount of air is drawn through the fuel bed of the combustion chamber, resulting in the most efficient conditions of operation.

Various other objects and advantages will become apparent as the description proceeds.

Referring now to the drawings forming a part of this specification, and illustrating certain preferred embodiments of my invention,

Fig. l is an elevational view showing my improved barometric draft control mounted in connection with a heating apparatus.

Fig. 2 is a front elevational view of the same.

Fig. 3 is a sectional view taken substantially along the line 3--3 of Fig. 2.

Fig. 4 is a fragmentary view similar to Fig. 3 and showing the valve blade in a partially open position.

Fig. 5 is a rear perspective view of the blade.

Fig. 6 is a rear perspective view of the frame member which supports the valve blade.

Fig. 7 is a fragmentary rear elevational view of another embodiment of my invention.

Fig. 8 is a sectional view taken substantially along the line 8-8 of Fig. '7. g

Fig. 9 is a fragmentary rear elevational view showing still another embodiment of my invention; and

Fig. 10 is an elevation taken substantially along the line Hl--I U of Fig. 9.

Referring first toFigures 1-5 inclusive, relative to one embodiment of my invention. the nu- -section 26.

meral Ii] indicates a stack of a furnace of any suitable type as used for the heating of dwellings, it being understood that draft controls of the type here lunder consideration are mounted for the best effect as closely as possible to the furnace. It will be obvious to those skilled in the art that the draft control may be mounted either on a vertical or horizontal portion of the stack.

A short pipe section l2 is inserted in the stack lil tov communicate therewith, the control indicated generally by the numeral l5 being arranged to close the free end of the pipe section I2.

A frame it is secured to the free end of the section l2 by any suitable means, as, for example, by wire er other suitable securing means l1, the frame Iii having a flange I8 overlapping the edge of the pipe l2, an inwardly extending flange i9 and a portion 2t lying in a plane transverse to the axis of the pipe i2. A pair of guide plates 2l, 2! is bent inwardly from the portion 2o, and slots 23, 23 are also formed in the lower part of the Above the slots 23 is formed a pair of knife edge bearing notches 24, 2li.

A damper blade indicated generally by the numeral 25 is mounted in the frame, this blade comprising a fiat Hportion 26 having a peripheral flange 21. This blade may be embossed as at 28 for stiifening purposes, and a hinge member 29 -is secured to the lower portion of the plate 26 as by spot welding. The hinge member 29 has inwardly bent therefrom a pair of ears 32, 32, these to practically zero.

Also secured to the plate 26 is a counterbalance arm 36, carrying thereon an adjustable Weight 38. It will be apparent that various devices might be used for adjustably securing the weight 38 at different points along the arm 36, providing the desired amount of counterbalance7 according ,to the extent of the draft within the stack. In

the embodiment shown I have illustrated a thumb screw 39, but it will be obvious that a spring or other suitable means might be employed. A bumper 4t, formed of felt, rubber or other suitable material, is arranged on the bar 36, to prevent noise and absorb shock.

To mount the blade on the frame IB, it is merely necessary to arrange the hinge ears 32 in such a manner that the journal portions 35 engage in the notches 24. It will be seen that the blade 25 fits substantially within the opening of the frame I6, and obviously we have selected only one of many suitable shapes which might be employed. The tongues 34 are so designed that when the blade has been drawn inwardly by the suction of the draft within the stack, as seen in Fig. 4, these tongues 34 may pass through the slots 23, thus permitting the blade to have a free floating support on the minimal bearing surfaces provided by the notches '24 and journals 35. These notches 24 serve to position the blade and retain it against lateral movement, and the arrangement of the tongues 34 and slots 23 prevents disengagement of the blade from the frame when the former is fully in open position. It should be noted that the hinge member 29 is so designed that the tongues 34-at no time engage against the edges of the slots 23, thus eliminating a possible cause of friction. The only exception to this condition would be in the event that a sudden draft might draw the blade violently inwardly, producing a tendency for the blade to jump out of its seat. In such an event the tongues 34 would be retained by the engagement against the upper edges of the slots 23, thus effectively preventing disengagement.

The construction shown is substantially selfcleaning, improves the smoothness of its bearing surfaces with use, and permits the blade to be quickly removed should it be necessary to clean the stack or the blade itself, by simply lifting it from its seat.

The principle of operation of controls of this 1,;

type is Well known. As the draft increases on the smoke pipe side of the blade, the blade tends to tilt inward. This decreases the draft Within the smoke pipe in the same manner as a check damper and this control is then reflected into the furnace or combustion chamber. The opposite conditions are obtained if, for any reason, the draft decreases; that is, the blade tends to tilt outwardly or close. The intensity of the draft is manually set by moving the adjusting weight closer to or away from the pivot point, raising the weight to reduce draft, lowering the weight to increase draft. The damper then automatically maintains that draft intensity,

Referring now'to Figs. 7 and 8, I have shown here a slightly different arrangement without departing from the general principle of my invention. In this case the blade 25a has lateral flanges U bent inwardly therefrom, these flanges tapering from top to bottom as -seen best in Fig. 8

so as to be of maximum weight in the lower portion thereof where the flanges are perforated to provide an entrance slot 52 and a more or less pear-shaped aperture 53, forming a pairof opposed arcuate tongues 55, 55. The frame 16a, is provided with a pair of notches 24a which engage in the apertures 53, and below these notches 25a are openings 23a. Counterweight bar 36a is secured by any suitable means, in this case, by means of screw 51 extending through a tongue 58 stamped out from the face of the blade 25a.

It will be seen that the embodiment just described functions like that of Figs. 1-6, inclusive, with the exception that one of the tongues 55, 55 extends through the corresponding aperture 23a substantially at all times, and hence it is practically impossible for the blade to become disengaged, no matter how violently it may be swung about its axis.

Figures 9 and 10 show a very` similar arrangement except that the hinge members 321) are formed as substantially circular arcuate tongues 52, 52 with an entrance slot 65 and a substantially circular journal aperture S1. The frame llb is provided with notches 24h and circular apertures 23h to accommodate the hinge members as before.

It will be seen that in all of the embodiments which I have described there is provided hinge means with a minimum of bearing surfaces, so that the blade will respond to the slightest variations in conditions within the stack. Hence, I am able to control the efficiency of the fire with greatest accuracy. Furthermore, it Will be apparent that I am able to produce my device most inexpensively, mostly from stampings.

Various other changes may suggest themselves to those skilled in the art, and hence I do not wish to be limited to the specific forms shown or uses mentioned, except as indicated by the appended claims.

I claim:

1. A draft control comprising in combination a frame having a horizontal upstanding ledge forming a hinge bearing and a valve blade balanced within said frame, said blade having a pair of hinge plates lying in spaced vertical planes transverse to that of said ledge, each hinge plate having an aperture therein serving as a bearing seat in engagement with said ledge and also having an entrance slot communicating With said aperture, said hinge members being so formed adjacent to said aperture and slot that the blade may quickly be manually attached to and removed from the frame but is not readily detachable therefrom in normal rocking action.

2. A device, as defined in claim 1, wherein said ledge is provided with a pair of relatively widely spaced notches, forming knife edge seats, and the blade has a pair of hinge members supported by said seats for substantially frictionless rocking movement.

3. A device, as dened in claim 2, wherein said frame is provided with perforations below each of said seats, and each of said hinge members has a tongue extending through the corresponding perforation of the frame when the blade is rocked.

4. A device, as defined in claim 3, wherein each of the hinge members has a pair of tongues with a notch therebetween to permit mounting and removal of the blade, one of said tongues extending through the corresponding perforation of the frame when the blade is substantially closed and the other tongue extending through said perforation when the blade is rocked to an open position, whereby accidental displacement of the blade is substantially prevented.

5. A device, as denned in claim 4, wherein said hinge members are formed by deforming marginal portions ofthe blade.

6. A draft control comprising, in combination., a frame having a horizontal upstanding ledge disposed within said frame and forming a hinge bearing, and a valve blade balanced on said bearing as a pivot, said blade having a pair of hinge plates disposed in spaced vertical planes transverse to that of said ledge and each having an aperture therein serving as a bearing seat in engagement with said ledge, said ledge having apertures spaced correspondingly to said hinge plates and positioned to permit passage of a portion of the latter when the blade is rocked to extreme positions.

7. A draft control comprising in combination a frame` adapted to be inserted in an opening in a pipe section, said frame having an upstanding ledge therein with a pair of spaced notches formed in the upper surface thereof serving as hinge bearings, a valve blade arranged in said opening for pivotal movement, said blade having hinge members rockably supported in said notches, each of said hinge members having an aperture providing bearing surfaces and also having an opening communicating with said aperture so as to obviate accidental displacement of the blade.

8. A combination as defined in claim 7 wherein said ledge is provided with a slot under each of said notches and wherein said openings in the hinge members denne a tongue extending through an adjacent slot when the blade is rocked through a sufficiently Wide angle.

9. A combination as defined in claim 8 wherein said opening and aperture define a pair of opposed tongues, one of which tongues extends through an adjacent slot' when the blade is in repose and the other of which tongues extends through said slot when the blade is rocked through a relatively wide angle.

10. A draft control comprising in combination n hinge members roclrably supported in said notches, each of said hinge members having an aperture providing bearing surfaces and also having an opening communicating with said aperture so as to obviate accidental displacement of the blade.

11. A combination as defined in claim 10 wherein said ledge is provided with a slot under each of said notches and wherein said openings in the hinge members define a tongue extending through an adjacent slot when the blade is rocked through a sufliciently wide angle.

12. A combination as defined in claim 10 wherein said opening and aperture denne a pair of opposed tongues, one of which tongues eX- tends through an adjacent slot when the blade is in repose and the other of which tongues eX- tends through said slot when the blade is rocked through a relatively wide angle.

ARTHUR O. DADY.

REFERENCES CITED The following references are of record in the lile of this patent:

UNITED STATES PATENTS Number Name Date 1,574,711 Steele Feb. 23, 1926 FOREIGN PATENTS N uinbei' Country Date 388,062 Germany Jan. 10, 1924 502,187 Germany July 9, 1930 

